Jack



June 26, 1928. 1,674,822

T. W. GRAY JACK Filed Jan. 14, 1926 50 L J' LJ 5 Fie. 3

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Patented June 26, 1928..

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THOMAS W. (Bi-IEtAY,v OF LOUPUREX, TENNSYLVANZA, ASSIGNOR TO PITTSBURGH COAL COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYL- VANIA.

JACK.

Application filed January 14, 1926. Serial No. 81,137.

My invention relates to jacks, and. while the jack of my invention is not limited in its field of service to any particular industry, it finds practical application in the operation of coal mines, and I show and describe a jack of my invention adapted to such service.

In the accompanying drawings Fig. 1 is a view in plan, and Fig. 2 a view in side elevation of a jack of my invention. Fig. 3 is a view to larger scale and in vertical section of the same machine, the plane of section being indicated in Fig. 2 by the line III- 11.

The jack includes certain features common to machines of this sort, namely a screwthreaded shaft 1 provided with a foot 2 and adapted to stand vertically on a horizontal supporting surface; a head 3 provided with a sleeve-likeextension 30, adapted to move telescopically upon shaft 1; and a nut 4: engaging the screW-thread upon shaft 1 and adapted by rotation to move up and down upon the screw-threaded shaft, and as it moves, to carry with it the head 3. In this instance the head through its sleeve-like extension 30 rests by gravity upon the nut 4, and so is in the service particularly contemplated responsive to nut movement. The nut is provided with sockets 410, for the reception of the end of a bar by which the nut may be turned easily when great Weights are to be raised. These are features known to the art, and are here set forth in an exemplary way. My invention is applicable to jacks of various particular types, and this particular type will serve by way of example.

It is in the particular construction of the head, adapted to facilitate the use of the jack that my invention is found. The head is a two-part head, and includes'not merely the member 3 which is provided with the sleeve-like extension, but includes also a member 31, adapted to engage the work immediately. To that end the member 31 is provided with a bearing surface ofsuitable extent, arranged in a plane parallel with the sole of the foot 2. The two members 3 and 31 meet on a plane which is inclined to the axis of the machine-ordinarily a vertical axis, as it here is shown to be, or substantially such. That axis is in the line of strain when the machine is in service. The oblique plane of meeting is indicated in Fig. 3 at 32. l Vhen the machine is under compressive strain, it will be understood that the member 31 will tend to move downward upon surface 32, that is to say, from right to left, Fig. 3.

A latch 5 fs provided, adapted to enter a recess formed in member 3 to receive it, and the latch when in place-serves as an abutment against which member 31 rests in elevated position upon the oblique plane 32, and it holds member 31 against the downward movement mentioned. a

The latch 5 is borne by member 31 upon a toggle composed of links 51 and 52. The link 51 is pivoted at its upper end to member 31, and the link 52 is pivoted at its lower end to the latch 5, and the parts are so proportioned that when the toggle is extended and in vertical position (that is to say, parallel with the axis of the machine) the latch 5is in position in the recess formed in member 3 to receive it. This locked position is shown in Fig. 3 and will be understood at a glance.

A block 6, rotatably borne by head 31, serves as a toggle-swinging member. It is rovided with a wrench-seat 60, through which rotation may be effected at will, and it is provided also with a cam surface 61 adapted to bear upon the prolonged pivot pin of the toggle joint. The parts being in the position shown in Fig. 3, it will be perceived that rotation of block 6 in clockwise direction will effect the throwing of the knee joint of the toggle from right to left, the collapse of the toggle, the withdrawal of latch 5 from its seat in member 3, and the release of member 31. Member 31 then will slide down incline 32, and the jack will be released.

The block 6 is provided with a hooked end 63 which when the parts are in the position shown hooks over the pivot pin 50, and secures the toggle against collapse. As the block 6 is turned clockwise the hook 63 is withdrawn, releasing the pivot pin. In ordinary practice the toggle will be secured against collapse both by the hook just described and also by such a proportioning of roof of a mine chamber.

the toggle members: that the toggle in the sustaining'position shown has passed slightly beyond the dead center and is kneed slightly to the right. Abutment against block 6 prevents collapse in that direction. And in order then to effect collapse in the intended mannerdescribed, the block 6 must be turned for a slight distance against the stress of the superposed weight. The block it will be seen is mounted for turning in a recess in member 31 formed to receive it.

The method of operation is apparent. The jack with the members 3 and 31 locked as shown in Fig. 8 may be applied as an ordinary jack is applied, to sustain, for instance, or to cooperate in sustaining the vVhen the jack is to be removed it is unnecessary to incur the delay of a. laborious turning of nutl. Instead, block 6 may be swung, and immediately the head members collapse in their relative positions, and the jack may be removed. The speed'with which the jack may be removed is a matter of great advantage and in many instances a matter which makes for safety in a dangerous situation.

I claim as my invention:

1. A jack including a foot and a head and screw-threaded means for effecting relative movement between them, the said head being composed of two members which meet on'a plane inclined to the axis of the machine, a toggle pivoted at one end to one of said members and a latch pivoted to the other end of said toggle, the said latch adapted when the toggle is extended to engage the other member of the head and when the toggle is collapsed to 2. A head for ajack including two members, one of which is providedwith a loadengaging face, the two members meeting in a plane oblique to such load-engaging face, a toggle pivoted at one end to one of said members and a latch pivoted to the, other end of said toggle, the said latch adapted when the toggle is extended to engage the other member of the head and when the toggle is collapsed to be withdrawn from such engagement, and means for swinging the toggle.

3. A head for a jack as defined in claim 2, the means for swinging the: toggle consisting ofa block borne rotatably in one of the head members and being provided with a cam surface adapted to exert a thrust upon the toggle.

4. A head for a jack as defined in claim 2, the toggle being provided with a prolonged pivot pin, and the means for swinging the toggle consisting of a block borne rotatably in one of the head members, theblock being provided with a hook adapted as the'block rotates alternately to 'hook 'over the prolonged pivot pin andto secure the toggle against collapse andto release the pivot pin, and the block being'fu'rther provided with a cam surface adapted as the block rotates to abut uponsaid prolonged pivot pin and by abutment to shift the pivot pin across the dead center of the toggle.

In testimony whereof I have hereunto set my hand. i

THOMAS w. GRAY. 

